The present invention relates to the imaging arts. It finds particular application in conjunction with characterizing output image output devices to accommodate variable qualities of different output media, and will be described with particular reference thereto.
Color printers are characterized by printing a number of colors with given CMYK values, measuring the colors obtained and generating a characterization function from CMYK to some device independent coordinate system, such as CIELAB. The final color correction that inverts the characterization function is often implemented as a 3D look-up table that maps CIELAB to CMYK.
Each characterization of a printer or image output terminal (e.g. xerographic, or lithographic machines) must be done for a specific substrate. If a user decides to use a substrate different from that used in the characterization, the color output error will depend upon the magnitude of the differences between the properties of variables inherent in the substrate used in the characterization and that used for printing.
Presently, many users ignore the change in substrate and use the original characterization on each new substrate. This approach is far from satisfactory and typically causes errors in the fidelity of the output characterization of the printer, the only solution currently available is to repeat the entire characterization procedure for each new substrate. Beyond requiring instruments not readily available to end users, this is a difficult process.
There are many factors that make characterizing a printer difficult. Some factors are uncontrollable and often unpredictable, printer drift is one such factor. The printer may change daily, or even hourly depending on the environmental conditions and throughput. Location sensitivity is another unpredictable factor, how the print will vary depending on where the toner is laid down on the substrate.
The colorants used in the printer are of great importance, and existing printer characterization models rely upon building a model of calorimetric response as a function of colorant and cross-colorant combinations, as specified by reflectance or tristimulus values.
Even if one were able to build a printer that did not drift, that had uniform location sensitivity, with a stable, predictable set of colorants, there is still one variable that must be accounted for the print substrate.
The substrate is one of the most variable factors involved in the printer characterization. The printer""s tone response is influenced by variables such as substrate color, weight, morphology, dimensional stability, coating technology, to name but a few. Each characteristic will in itself vary depending on the substrate. Thus, the printer""s performance is, in large measure, dependant on variable characteristics of the output media (e.g. paper, card stock, or even cloth) Peak fidelity is accordingly only achieved through the difficult process of complete recharacterization.
The above problem is solved in a method of adjusting a printing device in response to a variable property of an output medium. The variable may include color, reflectance, texture, weight, and/or a combination thereof associated with the output medium. The method includes storing a reference characterization of at least one measured value associated with a reference output medium. An output value adjusted for the variable property of the desired output medium is then determined based on data including the reference characterization of the reference medium. Based on the determined output value, the desired output value is printed on the desired output medium.
In accordance with another aspect of the present invention, an image production system includes a storage device for storing a reference color characterization of a reference substrate. The system further includes a mechanism for receiving a value associated with a second substrate. A processor in the system then determines an output value adjusted for the variable property of a desired output medium based on data including a reference characterization of the reference output medium.
One advantage of the present invention resides in adjusting a printer characterization based on a property of the output medium, including color, texture and/or weight, without having to repeat an entire characterization process.
Another advantage of the present invention resides in enhanced fidelity of an output image with respect to an input image, with minimum, if any, user involvement.
Still further advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.